Impact of seaweeds extracts applied to grapevine cv Tempranillo

The phenolic profiles of little known red grape cultivars, namely Garnacho, Moribel and Tinto Fragoso, which are autochthonous from the Spanish region of La Mancha (ca. 600,000 ha of vineyards) have been studied over the consecutive seasons of years 2013 and 2014. The study was separately performed over the skins, the pulp and the seeds, and comprised the following phenolic types: anthocyanins, flavonols, hydroxycinnamic acid derivatives (HCADs), total proanthocyanidins (PAs) and their structural features. The selected grape cultivars belong to the Vine Germplasm Bank created in this region in order to preserve the great diversity of genotypes grown in La Mancha.

Fungicides play a critical role in managing grapevine downy mildew caused by the oomycete Plasmopara viticola, a biotrophic and polycyclic pathogen with a high risk of fungicide resistance. Zoxamide, categorized as a low to medium resistance risk, disrupts cell division by inhibiting tubulin polymerization. Resistance to zoxamide is uncommon in field isolates. This six-year study (2017-2022) aimed to detect and quantify zoxamide sensitivity in P. viticola populations across varying resistance pressures in Italian grapevine regions. Analysis of 126 samples from 57 vineyards, mainly in North-Eastern Italy, revealed that most samples exhibited EC50, EC95, and MIC values below 0.1 and 10 mg/L of zoxamide, respectively. Nineteen vineyards showed reduced sensitivity (MIC>100 mg/L), but only four samples were characterized by 24-54% resistant oospores at >100 mg/L of zoxamide.

Berry maturation in warm areas takes place very early, when temperatures are still high and favorable for carbohydrate synthesis and accumulation in the berries, but not as favorable for maintaining high titratable acidity or low pH, or for increasing berry polyphenol content. Different canopy management techniques have been proven to delay berry maturation at the expense of yield (severe canopy trimming, late spring pruning to induce sprouting of dormant buds, etc.). Minimal pruning delays berry ripening by highly increasing yield and by reducing the leaf area to fruit ratio.

In white wines, Verdejo wine stands out because of its high content in total amino acids. The total content in biogenic amines was low in all wines analyzed and putrescine was the predominant biogenic amine.

The study described the effect of sensory analysis on commercial ‘Sauvignon blanc’ vineyards within the Stellenbosch Wine of Origin District. The sensorial evaluation of the berries was able to give a description of each parcel type and relate it to the cultural practices.